This update with a size of 360 MB should iron out the bugs and performance issues in the Marshmallow build of Note 4. Being a security patch, you should expect some security fixes as well in this update.

The build number changes to GDTS1DPD2 after the update. This security update is rolling out over-the-air and is also available on a PC through Samsung Smart Switch. If you haven’t received the update yet, you can check for it manually by going to Settings > About device > Check for updates.